This invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to developer and toner compositions containing certain amorphous polyimide resins, and process for the preparation thereof. In embodiments, there are provided in accordance with the present invention, toner compositions comprised of certain polyimide resins, and pigment particles comprised of, for example, carbon black, magnetites, or mixtures thereof, cyan, magenta, yellow, blue, green, red, or brown components, or mixtures thereof thereby providing for the development and generation of black and/or colored images. In embodiments, there are provided in accordance with the present invention polyimide resins illustrated by the formula, and melt condensation processes thereof ##STR3## wherein X is ##STR4## thus X can be benzophenone, oxydiphthalic, hexafluoropropane diphenyl, diphenyl sulfone, or biphenyl; and X is attached to four imide carbonyl moieties; and R is an alkyl, an alkylene, such as an alkylene oxide with from about 1 to about 25 carbon atoms, such as ethylene, diethylene oxide, triethylene oxide or a polyoxypropylene; and m represents the number of repeating segments, and can be a number of from about 50, preferably 100 to about 10,000. The toner compositions of the present invention in embodiments possess a number of advantages including gloss switching characteristics, which is the ability of a toner to provide either low or high gloss performance, low melting characteristics, excellent blocking characteristics, excellent admix characteristics, excellent nonvinyl-offset properties, and low relative humidity sensitivity such as from about 1.01 to about 2.3. The toner compositions of the present invention can in embodiments be generated by a preparative process involving the melt polycondensation of about 1 mole equivalent of dianhydride, such as benzophenone dianhydride, and of from about 1 mole equivalent of an alkylene diamine, or preferably a diaminoterminated alkylene oxides such as the diaminoterminated polypropylene oxide or diaminoterminated polyethylene oxide available from Texaco Chemicals as JEFFAMINE D-230.TM., D-400.TM., D-700.TM., EDR-148.TM., and EDR-192.TM. as illustrated by the formula The aforementioned polyimides of the present invention exhibit in embodiments a number average molecular weight of from about 1,500 to about 50,000 and preferably 20,000 grams per mole as measured by vapor phase osmometry, and a glass transition temperature of from about 40.degree. C. to about 80.degree. C., and more preferably of from about 50.degree. C. to about 65.degree. C. as measured by the Differential Scanning Calorimeter. In another embodiment, the polyimides can be generated by a preparative process involving the reaction of about 0.7 mole equivalent to about 1 mole equivalent of dianhydride, such as benzophenone dianhydride, and of from about 0.7 to about 1 mole equivalent of an alkylene diamine, or preferably a diaminoterminated alkylene oxide, such as the diaminoterminated polypropylene oxide, or diaminoterminated polyethylene oxide available from Texaco as JEFFAMINE.TM., and optionally a comonomer, such as a symmetrical aromatic or cyclic monomer, such as pyromellitic anhydride selected in amounts of from about 0.1 mole equivalent to about 0.3 mole equivalent, and wherein the polyimide resin resulting possesses a number average molecular weight of from about 1,500 to about 50,000 grams per mole as measured by vapor pressure osmometry, and a glass transition temperature of from about 40.degree. C. to about 70.degree. C., and more preferably of from about 50.degree. C. to about 64.degree. C. as measured by the Differential Scanning Calorimeter. In one embodiment, the present invention is directed to a toner composition comprised of a pigment, charge control agent and polyimide resins as illustrated herein with low fixing temperature of from about 120.degree. C. to about 150.degree. C., low gloss such as from about 0 to 30 gloss units at rapid fusing speeds, such as from about 200 to about 350 millimeters per second, or high gloss, such as from about 31 to about 90 gloss units at slower fusing speed, such as from about 50 to about 180 millimeters per second, with nonvinyl offset properties and in addition, low relative humidity sensitivity such as from about 1.0 to about 2.3.
Examples of advantages of the toner composition of the present invention comprised of the polyimides include gloss switching characteristics, such as the ability to provide low gloss such as from about 0 to 30 gloss units at rapid fusing speeds, such as from about 200 to about 500 millimeters per second, and the ability to provide high gloss, such as from about above 30 to about 90 gloss units at slower fusing speed such as from about 1 to about 180 millimeters per second. Furthermore, the toner compositions of the present invention in embodiments possess low fusing temperatures, such as from about 120.degree. C. to about 140.degree. C., and therefore lower fusing energies are required for fixing thus enabling less power consumption during fusing, and permitting extended lifetimes for the fuser system selected. Furthermore, the toner compositions of the present invention possess a broad fusing latitude, such as from about 40.degree. C. to about 100.degree. C., with minimal or avoidance of release oil, which inhibits the toner from offsetting onto the fuser rollers usually associated with ghosting or background images on subsequent copies. Additionally, the fused images obtained with the toner compositions of the present invention in embodiments do not substantially offset to vinyl covers, such as those utilized for notebook binders, and such toners possess low humidity sensitivity ratios of from about 1 to about 2.3 as calculated by the ratio of the triboelectric charge in microcoulombs per gram of the developer after placed in a chamber of 20 percent humidity for 48 hours, to the triboelectric charge in microcoulombs per gram of the developer after placed in a chamber of 80 percent humidity for 48 hours.
In designing resins for toner composition, it is generally desired and/or required that the glass transition temperature of the resin be from about 50.degree. C. to about 65.degree. C., and preferably no less than about 55.degree. C., so that, for example, the toner particles do not aggregate, coalesce or block during the manufacturing, transport or storage process or until the toner is required for the fixing step. Additionally, low fusing characteristics are important, hence the resin should melt or flow as low in temperature as possible such as from about 130.degree. C. to about 145.degree. C. Moreover, low relative humidity sensitivity of toners is needed, such as from about 1.0 to about 2.3, so that the triboelectric charge is stable to changes in environmental humidity conditions. Additionally, in many instances, especially in highlight applications, low gloss documents are highly desired, that is from about 0 to 30 gloss units as measured by the 75.degree. Gardner Gloss Metering Unit. Also, in many instances, especially in process or pictorial color applications, high gloss documents are highly desired, that is, from about above 30, for example 31, to about 80 gloss units as measured by the Gardner Gloss Metering Unit. Toners which display low gloss properties are known, and are for the most part comprised of a styrene-(meth)-acrylate or styrene butadiene resin, or crosslinked polyesters and pigment. Moreover, toners which display high gloss characteristics are also known, such as those comprised of a linear polyester resin and pigment, or comprised of a styrene based resin and pigment, and fused at temperature of from about 160.degree. C. to about 180.degree. C. Although, copiers and printers can be designed with several toners, or different fuser designs such that both low and high gloss prints or copies are generated, this can be very costly and is not considered practical. In the present invention, toner compositions comprised of certain polyimide resins and pigments display both high gloss and low gloss characteristics depending, for example, primarily on the fusing speed of the fuser rolls during the transfix step. For instance, a toner composition comprised of a polyimide of the present invention and pigment displays low gloss characteristics of from about 0 to about 30 gloss units as measured by the Gardner Gloss Metering Unit, when the fusing speed is set at greater than about 200 millimeters per second. When the fusing speed is set between 100 and 180 millimeters per second, higher gloss is obtained, such as from about above 30 to about 90 gloss units. Hence, by systematically setting the fusing speed of a printer or copier by the press of a button, low gloss, a matte finish, or high gloss can be obtained. Furthermore, with the toners of the present invention in embodiments, low fixing temperatures, such as from about 130.degree. C. to about 150.degree. C., are utilized and need not be changed for the production of low or high gloss documents. Additionally, the polyimide toners of this invention display a broad fusing latitude such as from about 40.degree. C. to about 100.degree. C. with minimal or avoidance of release oil, which oil inhibits the toner from offsetting onto the fuser rollers usually associated with ghosting or background images on subsequent copies. Furthermore, the fused image obtained from the toner composition of the present invention in embodiments does not substantially offset to vinyl covers, such as those utilized for notebook binders, and these toners possess low humidity sensitivity ratio of from about 1 to about 2.3 as calculated by taking the ratio of the triboelectric charge, in microcoulombs per gram, of the developer after placed in a chamber of 20 percent humidity for 48 hours, to the triboelectric charge, in microcoulombs per gram, of the developer after placed in a chamber of 80 percent humidity for 48 hours. Toners with polyimide resins derived from a mesogenic dianhydride and organo diamine can exhibit low fixing of from about 120.degree. C. to about 140.degree. C., high gloss, such as from about 50 gloss units to about 80 gloss units, nonvinyl offset properties and low relative sensitivity, such as from about 1.0 to about 2.3. Moreover, by utilizing prior art toners comprised of styrene-butadiene or polyester resins and pigments, both high and low gloss documents may not usually be obtained by changing the speed of the fuser rolls, while maintaining the same low minimum fixing temperatures, as illustrated herein in Comparative Examples VIII and IX.
Illustrated in the following copending applications, the disclosures of each being totally incorporated herein by reference, are:
U.S. Ser. No. 144,075 , filed concurrently herewith, illustrates a toner composition comprised of a pigment and a crosslinked polyimide; and wherein the crosslinked polyimide can be obtained from the reaction of a peroxide with an unsaturated polyimide of the formula ##STR5## R is alkyl or oxyalkylene and m represents the number of monomer segments present and is a number of from about 10 to about about 1,000.
U.S. Pat. No. 5,348,930 illustrates a toner composition comprised of a pigment, and a thermotropic liquid crystalline polyimide of the formula ##STR6## wherein m represents the number of monomer segments present; X is a symmetrical moiety independently selected from the group consisting of phenyl, naphthyl, cyclohexyl, or bicycloaliphatic; and R is independently selected from the group consisting of alkyl, oxyalkylene and polyoxyalkylene.
U.S. Ser. No. 144,956, filed concurrently herewith, illustrates a toner composition comprised of pigment, and polyimide of the formula ##STR7## wherein n represents the number of monomer segments, and is a number of from about 10 to about 1,000; and R is alkyl, oxyalkyl, or polyoxyalkyl.
U.S. Pat. No. 5,348,831 illustrates a toner composition comprised of pigment, and a polyester imide resin of the formula ##STR8## wherein n represent the number of segments present and is a number of from about 10 to about 10,000; R' is alkyl or alkylene; and R is independently selected from the group consisting of an oxyalkylene and polyoxyalkylene.
Polyimide resins and, more specifically, liquid crystalline polyimide resins are also known, such as summarized and illustrated in the Encyclopedia of Polymer Science and Engineering, 2nd Edition, Volume No. 12, Published by Wiley (1985). However, these polyimide resins are aromatic and useful as high performance materials, and toner use is not described. Moreover, the polyimide resins of the present invention and, more specifically, polyimides with flexible diamino alkane moleties and also polyoxyalkylene moieties are not believed to be disclosed.